A polycarbonate resin, which is a polycarbonate ester-based polymer of bisphenol A among thermoplastic resins, is known to exhibit excellent mechanical properties, impact resistance, dimensional stability, electrical properties and moldability. Further, because the polycarbonate resin is able to maintain its physical properties over a wide range of temperature, and exhibits self-extinguishing property, it is used as an engineering plastic material with a wide variety of applications.
In particular, a glass fiber-reinforced polycarbonate resin exhibits improved tensile/flexural strength, tensile/flexural modulus and heat resistance, and thus it can be properly used in the products that receive continuous load at high temperatures. However, glass fiber reinforcement may reduce impact strength, tensile elongation, toughness or the like, and also deteriorate flowability, resulting in poor moldability and processability. Additionally, the surface protrusion of glass fiber causes a surface roughness and vulnerability to an external impact during the general molding process, and thus there are many restrictions in its application to housing of various electrical•electronic products.
In order to improve flowability or the like, it has been suggested that a glass fiber reinforced polycarbonate resin composition is provided by using a low molecular weight polycarbonate resin. In this case, flowability and moldability can be improved, but impact resistance and chemical resistance can be rapidly reduced. It was also considered to use a general impact modifier having a core-shell structure together with glass fiber for the improvement of impact strength, toughness or the like. In this case, flowability and moldability are also reduced, and glass fiber breakage and resin degradation due to excessive shear occur during processing, and therefore, it is difficult to achieve impact resistance. Furthermore, there is a problem of poor surface roughness due to the surface protrusion of glass fiber.
Recently, as molded articles such as small electrical•electronic products or the like have become thinner and complicated, application of the above described conventional glass fiber-reinforced polycarbonate resin composition to the housing of these electrical•electronic products often caused flexure or deformation, or breakage during processing. The reason is likely to be a shrinkage difference between the flow direction and the direction orthogonal to the flow direction due to the glass fiber reinforcement.